private static Map<File, Set<File>> buildOutputDirectoriesMap(
     CompileContext context, ModuleChunk chunk) {
   final Map<File, Set<File>> map = new THashMap<File, Set<File>>(FileUtil.FILE_HASHING_STRATEGY);
   for (ModuleBuildTarget target : chunk.getTargets()) {
     final File outputDir = target.getOutputDir();
     if (outputDir == null) {
       continue;
     }
     final Set<File> roots = new THashSet<File>(FileUtil.FILE_HASHING_STRATEGY);
     for (JavaSourceRootDescriptor descriptor :
         context.getProjectDescriptor().getBuildRootIndex().getTargetRoots(target, context)) {
       roots.add(descriptor.root);
     }
     map.put(outputDir, roots);
   }
   return map;
 }
  private ExitCode compile(
      final CompileContext context,
      ModuleChunk chunk,
      DirtyFilesHolder<JavaSourceRootDescriptor, ModuleBuildTarget> dirtyFilesHolder,
      Collection<File> files,
      OutputConsumer outputConsumer)
      throws Exception {
    ExitCode exitCode = ExitCode.NOTHING_DONE;

    final boolean hasSourcesToCompile = !files.isEmpty();

    if (!hasSourcesToCompile && !dirtyFilesHolder.hasRemovedFiles()) {
      return exitCode;
    }

    final ProjectDescriptor pd = context.getProjectDescriptor();

    JavaBuilderUtil.ensureModuleHasJdk(
        chunk.representativeTarget().getModule(), context, BUILDER_NAME);
    final Collection<File> classpath =
        ProjectPaths.getCompilationClasspath(chunk, false /*context.isProjectRebuild()*/);
    final Collection<File> platformCp =
        ProjectPaths.getPlatformCompilationClasspath(chunk, false /*context.isProjectRebuild()*/);

    // begin compilation round
    final DiagnosticSink diagnosticSink = new DiagnosticSink(context);
    final Mappings delta = pd.dataManager.getMappings().createDelta();
    final Callbacks.Backend mappingsCallback = delta.getCallback();
    final OutputFilesSink outputSink =
        new OutputFilesSink(context, outputConsumer, mappingsCallback, chunk.getName());
    try {
      if (hasSourcesToCompile) {
        final AtomicReference<String> ref = COMPILER_VERSION_INFO.get(context);
        final String versionInfo =
            ref.getAndSet(null); // display compiler version info only once per compile session
        if (versionInfo != null) {
          LOG.info(versionInfo);
          context.processMessage(new CompilerMessage("", BuildMessage.Kind.INFO, versionInfo));
        }
        exitCode = ExitCode.OK;

        final Set<File> srcPath = new HashSet<File>();
        final BuildRootIndex index = pd.getBuildRootIndex();
        for (ModuleBuildTarget target : chunk.getTargets()) {
          for (JavaSourceRootDescriptor rd : index.getTempTargetRoots(target, context)) {
            srcPath.add(rd.root);
          }
        }

        final String chunkName = chunk.getName();
        context.processMessage(new ProgressMessage("Parsing java... [" + chunkName + "]"));

        final int filesCount = files.size();
        boolean compiledOk = true;
        if (filesCount > 0) {
          LOG.info(
              "Compiling "
                  + filesCount
                  + " java files; module: "
                  + chunkName
                  + (chunk.containsTests() ? " (tests)" : ""));
          if (LOG.isDebugEnabled()) {
            for (File file : files) {
              LOG.debug("Compiling " + file.getPath());
            }
            LOG.debug(" classpath for " + chunkName + ":");
            for (File file : classpath) {
              LOG.debug("  " + file.getAbsolutePath());
            }
            LOG.debug(" platform classpath for " + chunkName + ":");
            for (File file : platformCp) {
              LOG.debug("  " + file.getAbsolutePath());
            }
          }
          compiledOk =
              compileJava(
                  context,
                  chunk,
                  files,
                  classpath,
                  platformCp,
                  srcPath,
                  diagnosticSink,
                  outputSink);
        }

        context.checkCanceled();

        if (!compiledOk && diagnosticSink.getErrorCount() == 0) {
          diagnosticSink.report(
              new PlainMessageDiagnostic(
                  Diagnostic.Kind.ERROR, "Compilation failed: internal java compiler error"));
        }
        if (!Utils.PROCEED_ON_ERROR_KEY.get(context, Boolean.FALSE)
            && diagnosticSink.getErrorCount() > 0) {
          if (!compiledOk) {
            diagnosticSink.report(
                new PlainMessageDiagnostic(
                    Diagnostic.Kind.OTHER,
                    "Errors occurred while compiling module '" + chunkName + "'"));
          }
          throw new ProjectBuildException(
              "Compilation failed: errors: "
                  + diagnosticSink.getErrorCount()
                  + "; warnings: "
                  + diagnosticSink.getWarningCount());
        }
      }
    } finally {
      if (JavaBuilderUtil.updateMappings(
          context, delta, dirtyFilesHolder, chunk, files, outputSink.getSuccessfullyCompiled())) {
        exitCode = ExitCode.ADDITIONAL_PASS_REQUIRED;
      }
    }

    return exitCode;
  }